LEO:

Court physician to Grand Duke Ivan III. Vassilivich of Russia; executed at Moscow April 22, 1490. With the arrival at Moscow of the grand duke's second wife, Sophia Palæologus, niece of Constantine, the last Byzantine emperor (1473), active intercourse began between Russia and western Europe. In 1490, when the brother of the grand duchess, Prince Andreas of Morea, and the Russian ambassador to Rome visited the court of Moscow, they brought with them, besides some artists and mechanics, a physician from Venice, named Leo. He was a Jew by birth, and is mentioned by the Russian historians as "Mister Leon Zhidovin" (= "the Jew"). He was probably the first physician from western Europe to enter Russia.

Leo had to pay for his temerity with his life; for he fell a victim to the superstition of the Muscovites. Soon after his arrival he had an opportunity to show his skill. Ivan Ivanovich, the son of the grand duke, had the gout; Leo, placing too much faith in his skill, assured the grand duke that he could effect a cure, and pledged his head in case of failure. He treated the patient with herbs and drycuppings; but the prince became worse, and died March 7, 1490. At that time the people believed in the infallibility of medical science, and accordingly they accused the unsuccessful physician of ill-will. Leo was arrested, and, after the forty days of mourning had elapsed, was publicly beheaded at Bolvanov Place.